The invention relates to methods and devices for assessing one or more components of a selected tissue in an animal. The present invention permits non-invasive assessment of tissue components in a body structure containing multiple tissue types by assessing multiple regions of the animal's body for an optical characteristic of the tissue of interest and separately assessing one or more optical (e.g., Raman or NIR) characteristics of the tissue component for one or more regions that exhibit the optical characteristic of the tissue of interest.